It is generally known to a person skilled in the art of rolling bearings that single-row grooved ball bearings are rigid radial rolling bearings which cannot be dismantled and which are distinguished, above all, in that their radial and axial carrying capacity are equally high, and in that, because of their low friction, they have the highest rotational speed limits of all types of bearings. These grooved ball bearings have been known for a long time and consist essentially of an outer bearing ring and of an inner bearing ring and also of a number of balls which are arranged as rolling bodies between the bearing rings and which are guided at uniform distances from one another in each case in groove-shaped ball raceways in the inside of the outer bearing ring and in the outside of the inner bearing ring by means of a bearing cage. Radial ball bearings are filled with the balls in this case by means of the eccentric mounting method which became known from DE 168 499 and in which the two bearing rings are arranged eccentrically to one another, and the free space thereby occurring between the bearing rings is filled with the balls which are finally distributed at a uniform distance from one another on the pitch circle of the two ball raceways.
In practice, however, it has been shown that grooved ball bearings of this type nevertheless have limits in terms of the carrying capacity of the bearing on account of the small maximum installable number of balls which depends on the dimensions of the inner and of the outer bearing ring and on the ball diameter. In the past, therefore, a multiplicity of solutions were proposed, by means of which an increase in the carrying capacity of grooved ball bearings was to be achieved by means of an increase in the number of balls.
Such a possibility for increasing the number of rolling bodies on a radial rolling bearing became known, for example, from DE 43 34 195 A1. However, in this radial rolling bearing, designed per se as a single-row grooved ball bearing, the rolling bodies are not formed by balls, but by what are known as spherical disks which are formed with two side faces flattened symmetrically from a basic spherical shape and arranged parallel to one another. The width of these spherical disks between their side faces is in this case designed to be smaller than the distance between the inside of the outer bearing ring and the outside of the inner bearing ring, so that, when the bearing is being filled, the spherical disks can be introduced axially with respect to the bearing through the distance between the inner ring and outer ring into the bearing and can then be rotated through 90° into the raceways of the bearing rings. Since smaller distances between the individual rolling bodies can be achieved by means of this mounting method, therefore, overall, a higher number of rolling bodies can be introduced into the radial rolling bearing. In order, however, to avoid mutual contact and an automatic twisting of the rolling bodies transversely with respect to the running direction when the bearing is in operation, these rolling bodies, too, are held at uniform distances from one another and guided axially in a bearing cage. One of the proposed cage versions is in this case a bearing cage which is assembled from two ring halves and in which each of the ring halves has incorporated into it depressions which each correspond to the number of spherical disks and which engage into complementary centric depressions in the side faces of the spherical disks. The depressions in the side faces of the spherical disks are in this case connected to one another by means of a centric through bore through which the two ring halves are connected to one another by means of rivets, so that the spherical disks are fixed firmly with respect to one another in the circumferential direction. Between the depressions, the two ring halves of the bearing cage have in each case portions which run straight along the side faces of the spherical disks and by means of which in combination with the rivets serving as rolling axes of the spherical disks, an automatic twisting of the rolling bodies transversely with respect to their running direction is also avoided.
It has proved, however, to be a disadvantage that a bearing cage designed in this way has not taken into account the overall kinematic behavior, occurring under different bearing loads, of the rolling bodies designed as spherical disks, and therefore this bearing cage seems to be unsuitable for such special rolling bodies. Thus, for example, it was found that spherical disks, as rolling bodies in radial rolling bearings, run in a stable manner in their rolling body raceways, without wrenching movements, at higher rotational speeds and under uniform load, because of the gyroscopic effect which occurs, and do not require any axial guidance by the bearing cage. If, however, the bearing rotational speed falls below a permissible minimum rotational speed, a wobble effect, as it is known, occurs, in which the spherical disks tend to roll in a wavy manner in their raceways transversely with respect to the running direction. In this case, contact occurs between the raceway edges of the spherical disks and the straight portions of the two ring halves of the bearing cage, which generates frictional heat and causes a rise in the operating temperature in the radial rolling bearing. The friction between the spherical disks and the bearing cage may in this case become so high that, due to the frictional heat occurring, the permissible operating temperature of the bearing is overshot and the required lubricating film between the spherical disks, the bearing cage and the bearing rings breaks away locally or the lubricant is partially burnt, thus resulting in the destruction of the bearing cage and in the premature failure of the bearing. It was likewise possible to ascertain that, in such a bearing cage, a similar effect likewise leading to the destruction of the bearing cage and to the failure of the bearing occurs in that the spherical disks, by being clamped between the two ring halves on the rivets of the bearing cage, have no possibility of not being able to orientate themselves with the respective pressure angle of the radial rolling bearing in the event of a mixed radial and axial load on the radial rolling bearing. In the endeavor of the spherical disks to orientate themselves automatically with the pressure angle of the radial rolling bearing under such loads on the radial rolling bearing, there is likewise contact of the side faces of the spherical disks with the straight portions of the ring halves of the bearing cage and also contact of the centric through bore in the spherical disks with the rivets of the bearing cage, so that under such conditions, too, excessive frictional heat has been generated in the radial rolling bearing. Finally, a bearing cage of this type for spherical disks has also proved to be a disadvantage in terms of the production costs of radial rolling bearings equipped with such bearing cages, since its manufacture and, in particular, by means of rivets, its mounting which is to take place in the equipped bearing, are relatively complicated.